Engine fuel control utilizing compressor pressure, speed and temperature



Nov 24, 1959 F c REGGIO ENGINE FUEL CONTROL UTILIZING COMPRESSORPRESSURE, SPEED AND TEMPERATURE Original Filed Feb. 3, 1939 2Sheets-Sheet 1 Nov. 24, 1959 C. REGGIO F. 4 ENGINE FUEL CONTROLUTILIZING COMPRESSOR PRESSURE, SPEED AND TEMPERATURE Original Filed Feb.3, 1939 2 Sheets-Sheet 2 United States Patent ENGINE FUEL CONTROLUTILIZING COMPRES- SOR PRESSURE, SPEED AND TEMPERATURE Ferdinando CarloReggio, Tampa, Fla.

Application September 21, 1953, Serial No. 381,247, which is a divisionof application Serial No. 496,296, 'July 27, 1943, which is in turn acontinuation of application Serial No. 254,355, February 3, 1939.Divided 'and this application June 2, 1958,.Serial No. 739,041

17 Claims. (Cl. 123-103) This invention relates to liquid fuel controlsystems "and more particularly to liquid fuel metering or regulatingsystems for combustion enginesrthis application being "a division of myapplication Serial No. 381,247, filed September 21, 1953, which in turnis a division of Serial No. 496,296, filed July 27, 1943, and nowabandoned, and which in turn is a continuation of Serial No. 254,- 355,filed February 3, 1939, and also now abandoned.

This invention is of particular significance in connection with aircraftpropulsion powerplants which present complex control problems due to thewide range of variations in operating conditions to which they aresubject, such as ambient atmospheric pressure,.temperature, speed andload.

An object of my invention is to provide a control de- "Vice forautomatically varying the rate of liquid fuel flow in the powerplant inresponse to changes in a combination of various operating conditions.

It is a further object of this invention to provide a ffuel controlutilising engine speed, temperature and compressor pressure asparameters of engine operation for controlling the flow of fuel.

Another object is to provide a control device, for combustion powerplantwhich automatically varies the rate of liquid fuel flow to secureoptimum ratio between fuel flow and air flow' under varying operatingconditions and maintain the temperature level of the power- ;plantwithin safe limits.

It is a further object of this invention to provide a f fuel controlwhich is readily adaptable for control of different types of combustionengines or powerplants with only minor and routine modifications,adaptations and adjustment of the system.

The above and other objects of the invention will {-be apparent as thedescription proceeds; and while I have illustrated and described thepreferred embodiments of the invention as they now appear to me, it willbe understoodthat such changes may be made as fall within the scope ofthe appended claims. In the following description and in the claimsvarious details will be identified by specific names for convenience,but

they are intended to be as generic in the application as the art willpermit.

in the drawings, Figure 1 is a sectional elevation of a "fuel flowcontrol system according to the invention, Figure 2 shows a componentresponsive to variations of pressure and if desired also responsive tochanges of temperature in the compressor section of the powerplant,Figure 3, in part a section along line 55 of Figure 2, indicates aspeed-responsive component, and Figure 4 indicates a modified form ofthe spring 99 of Figure 1.

As indicated in Figure 1, a fuel pump 48 is connected by a low-pressureline 51 to receive fuel from a tank -'-50, and discharge pressure fuelinto a fuel manifold 45 *leadingto injection units or nozzles throughwhich -fuel'is sprayed into the combustion chamber or other suitableportion'of'thepowerplant at a ratewhich varies .with the fuel pressure.

charge pressure and temperature.

The injection units or nozzles 70 are no part of the present invention.One form there- 'of is described in my said parent application SerialNo.

496,296. Another suitable type, well known in the art, consistsessentially of a calibrated orifice through which a continuous spray offuel is discharged into the air stream or othere place of utilization ofthe engine.

The discharge and inlet ports of the fuel pump 48 are connected througha by-pass conduit controlled by a valve having a slidable element 72biased toward closed position by a spring 73 and actuated by means of abellcrank lever 74. The capacity of the pump 48 is substantially largerthan the maximum fuel requirements of the powerplant, hence excess fuelis constantly flowing through the by-pass, and the fuel pressure in themanifold 45 may be controlled at will by variably positioning the valve72. The fuel pump 48 may be driven as usual from the powerplant orengine, which is provided .with an air compressor or blower 61 supplyingair for combustion through a conduit or induction system 62 to one ormore cylinders or combustion chambers 60. A housing communicates througha large duct 81 with the air conduit 62 and contains air at compressordis- An evacuated resilient bellows 82in said housing acts on a lever 83to operate a pilot valve having discs 84 and 85 which control admissionof oil under pressure, through lines 87 and 88 connected to a highpressure system, to either side of piston 86, while a low-pressure line89 is arranged to drain oil back to the sump. A floating or follow-uplever 90 is connected at its opposite ends with the pilot valve and withthe piston 86, respectively, and at an intermediate point with a rod 91connected through a variable-ratio lever mechanism 92 and a rod 93 withthe bell-crank lever 74 which controls the fuel regulating valve 72.

Also included within the housing 80 there is a resilient bellows 95which contains a definite weight of gas or other thermally expansiblefluid, normally held at constant volume. The housing 80 is preferablyheat-insulated, and since it is connected to the induction system 62bymeans of a short conduit 81 of large diameter, eddy currents andtubulence set up by the high-velocity 'air flow produce an activethermal exchange, by concluction and convection, which maintains thefluid within the bellows at the same temperature as in the inductionsystem 62. The absolute pressure in the bellows is thereforeproportional to the absolute air inductionternperature. The bellows 95and a geometrically similar but evacuated bellows 96 act against eachother and on'a lever 97 to operate the rod of a pilot valve controllinga servo mechanism 102 similar to the servo motor 86 already described indetail. Hydraulic medium :is led thereto under pressure and drainedtherefrom as indicated by the arrows. The pressure of the air within thehousing 80 acts in opposite directions on the bellows 95 and 96 therebybalancing out the eflect of any change of such pressure, so that theload transmitted to the lever 97 is only dependent upon the inductiontemperature. The servo piston 102 operates on a lever 98 to vary thedistance of the upper end of rod 93 from the fulcrum of lever 92. Afollow-up spring 99 connecting the lever 98 with the pilot valve 100balances the load transmitted by the bellows assembly 9596 to the pilotvalve and is so designed that the operating distance of rod 93 from thefulcrum of lever 92 is maintained proportional to the actual absoluteinduction temperature. Any change in said temperature actuates thebellows 95 and the servo mechanism 102 to rotate the lever 98 and varythe load of spring 99 until the balance 3 of rod 100 of the pilot valvein its neutral position is restored.

The lower end of the rod 93 is provided (like the upper end thereof)with a roller, and engages the horizontal arm of the bell-crank lever74. A lever 137 has an upper arm which is connected with the rod 93 andis arranged to vary the elfective distance of the rod 93 from thefulcrum of lever 74 so as to alter the effective ratio of the bell-cranklever. The device operates as follows: the evacuated resilient bellows82 exerts on the pilot valve 94 an upward load which is proportional tothe air induction pressure. In normal operation the pilot valve 94 ismaintained in equilibrium in its neutral position by a downward load ofequal magnitude exerted thereon through the various elements 9093 and 74by the fuel pressure applied to the inner end of the regulator valve 72.Thus, for a given adjustment of levers 9S and 137, the air inductionpressure (which is a measure of powerplant air flow) and the fuelpressure in the fuel manifold 45 (which is a measure of powerplant fuelflow) are proportional. Thus, if the pressure of the air in theinduction system 62 decreases, due for example to climbing of theaircraft to higher altitude, the bellows 82 expands and the pilot valve94 moves downward, draining pressure oil from the lower chamber ofcylinder 86 and admitting pressure oil to the upper chamber thereof. Asa result, the power piston 86 moves downward, causing, through elements9093, counter-clockwise rotation of the bell-crank lever 74 and outwardmotion of the valve 72 to increase the flow of by-passed fuel. Hence therate of powerplant fuel flow decreases, and so does the pressure in thefuel manifold 45, thus decreasing the fuel pressure load exerted uponthe inner end of the valve 72 and in turn the magnitude of the downwardload transmitted from the valve 72 to the pilot valve 94 in proportionto the decrease of induction air pressure, whereupon the pilot valve 94returns to neutral position and stops the hydraulic cylinder piston 86.Conversely, an increase of induction air pressure, due for example to adescent of the aircraft to lower altitude, causes the same device toincrease the fuel pressure in manifold 45 so as to increase the rate ofpowerplant fuel fioW in the desired relation to increasing powerplantair flow.

As already stated, the lever 97 actuated by the bellows assembly 9596exerts upon the pilot valve 100 of the servo-motor 102 an upward loadwhich is proportional to the induction air temperature. In normaloperation, that is, under steady temperature conditions, said load isbalanced by the biasing effect of the compression spring 99, and thepilot valve 100 is in neutral position. An increase of inductiontemperature causes a proportional increase of pressure within bellows 95and also in the upward load applied to the pilot valve 100. Hencebellows 95 expands, the companion bellows 96 contracts, and the pilotvalve 100 is lifted to a position in which the elastic reaction due tothe resilient deformation of the bellows balances the difference betweenthe upward load transmitted to the pilot valve 100 due to the fluidpressure within bellows 95 and the load of spring 99. Oil under pressureis admitted above the piston 102 of the servo-motor so as to actuate thepiston and rotate the lever 98 counterclockwise, thereby increasing theload of the compression spring 99 by an amount proportional to theincreased induction temperature, whereupon the pilot valve 100 returnsto neutral position and stops the piston 102. The lever 98 has a lowerarm which is connected to the upper end of the rod 93 and is arranged tovary the distance of the rod 93 from the fulcrum of lever 92 inproportion to the variations of temperature in the air induction system62. Thus the upward load applied by lever 92 to the rod 93 is maintaineddirectly proportional to the absolute pressure and inverselyproportional to the absolute temperature in the induction system 62, andis therefore proportional to the air density therein. Hence, for a givenposition of lever 137, the structure so far described operates tomaintain the pressure in the fuel manifold .45 at all times proportionalto the air induction density;

In certain engine applications it may be desirable to vary the rate offuel flow as a different function of air temperature, for instance ininverse proportion to the square root of such temperature. Variouscharacteristics may be obtained by using springs 99 of differentdesigns. As indicated at Figure 4, the spring 99' may be formed withuniform coil diameter and variable pitch such that within the operatingrange the number of free coils is inversely proportional to the springdeflection, thus causing the fuel pressure to vary in inverse proportionto the square root of the air temperature. If, on the other hand, it ispreferred to use a conventional spring 99, any desired relationshipbetween the angular position of lever 98 and the corresponding distanceof rod 93 from the fulcrum of lever 92 may be obtained by resorting to acam mechanism arranged substantially as indicated in connection withFigures 2 or 3.

The lower arm of lever 137 is connected through a lost motion devicesuch as a pin engaging an elongated slot 138 formed at one end of a rodactuated by a pilots lever 78. A tension spring 139 exerts a biasingload on the lever 137 tending to rotate the same clockwise. By operationof the manual lever 78 the pilot or operator may rotate the lever 137 soas to vary the distance of rod 93 from the fulcrum of the bellcranklever 74 thereby controlling the ratio between fuel flow and air flow.However, such arrangement, in which the adjustment of the fuel-air ratioof the combustible mixture is left to the arbitrary choice of the pilotor engineer is not the best suitable in connection with aircraftpropulsion powerplants. Accordingly, one of the objects of the inventionis to provide, in combination with the previously disclosedarrangements, means responsive to one or more engine operativeconditions, such as the air pressure or density in the inductionmanifold, the engine speed, the engine cylinder temperature, whereby theadjustment of the mixture control lever 137, and in turn the fuel-airratio, may be automatically controlled and vary as a predeterminedfunction of said operating condition or conditions. Operation of theengine with best economy mixture is possible over a certain range ofpower, beyond which the engine cannot safely be operated withoutresorting to some additional enrichment of the mixture to suppressover-heating and detonation. A temperature responsive element 130,mounted in suitable location such as on a cylinder head or near anexhaust port, is connected with a bellows 131 placed to act against anevacuated bellows 132 so that changes in the pressure surrounding thebellows act in opposite directions thereon and have no effect on theiroperation. Temperature changes about element operate the bellows 131 andin turn the pilot valve 133 of a servo'mechanism similar to thosealready described in detail to control the angular adjustment of lever134, of cam 135 and to vary the load of the spring 136 acting on thepilot valve 133. An increase in temperature of the element 130 lowersthe pilot valve 133 and in turn rotates the lever 134 clockwise therebyincreasing the load of spring 136 until the balance of the pilot valve133 in its neutral position is restored. The cam 135 is adapted tooperate the lever 137 so that for each temperature of the element 130 itdetermines a corresponding predetermined minimum possible value of thefuel-air ratio. Because of the lost motion connection provided by theelongated slot 138, the temperature control device 130136 permits manualvariation of the rate of fuel flow by means of the pilots lever 78 up toa predetermined operating temperature of the powerplant but is arrangedto over-ride said lever 78 and take over control of the lever 137 attemperatures above that value in order to prevent excessive over-heatingof the power-plant Evidently, the point at which the temperature controldevice. takes over control is dependent upon the setting of the manuallever 78. i The rotatable cam, actuating the, horizontal arm of lever137- may be provided with a warped or doublecurvature surface, and anadditional mechanism, such as indicated in Figure 3, may be used inorder to vary the axial position of the cam. Such as arrangement makesit possible to alter the rate of fuel flow automatically as any desiredfunction of two independent variables or parameters or operatingconditions of the powerplant, said function being determined by theconfiguration of the three-dimensional cams Figure 2 shows a rotatablecam 146 which, like the cam 135 of Figure l, is adapted to. engage thehorizontal arm of lever 137 through a lostmotion connection. bellows141, evacuated totally or in part and enclosed in a housingcommunicating with the engine air induction system 162 on the dischargeside of the compressor 61, operates a pilotvalve 142 of a servomechanism similar to those already described, whereby an increase incompressor pressure raises the pilot valve 142 and causescounter-clockwise rotation of lever 143 until the increasing load of thetension spring 144 restores the balance of the pilot valve 142 in itsneutral position. Angular positioning ofthe earn from the lever 143 maybe obtained by securing the latter to an externally splined sleeve 147rotatably mounted on an engine driven shaft 145. The cam 146, which hasa three-dimensional surface, is, slidably mounted upon the splines ofthe sleeve 147, so that the angular setting of the cam is determined bymeans of the lever 143 in. accordance with air induction or compressorpressure, while the axial adjustment thereof is determined by speedresponsive means such as a governor 148 driven from the engine orpower-plant through a shaft 145. The governor 148 controls the pilotvalve 149 of a servo mechanism. whereby an increase in engine speeddisplaces the pilot valve to the left and causes the lever 15010 rotateclockwise until the increasing load of the tension spring 151 returnsthe pilot valve 149 to its neutral position. The cam 146 thereforedetermines for each value of induction pressure and speed conditions acorresponding predetermined or minimum value of the fuel-air. ratio. Inthe preferred embodiment the cam configuration is such that in thecruising range of induction pressure and engine speed combinations suchminimum .value corresponds substantially to the best economy mixture,while for combinations of engine speed and induction pressurecorresponding to higher power output the minimum fuel-air ratioobtainable will be higher than that corresponding to best economymixture. Due to the lost motion connection provided by the elongatedslot 138 and spring 139, the cam is adapted to over-ride the manuallever 78 and take over control of the lever 137 under predeterminedspeed and pressure conditions 'of the powerplant. The particular pointat which control of lever 137 shifts from manual to automatic evidentlydepends upon the setting of the pilots lever 78, And where the bellows141 is not entirely evacuated but contains fluid, it willbe actuated inresponse to variations not only in the induction air, pressure but alsoinresponse to induction air temperature changes.

Obviously, the structure disclosed in connection with Figure 3 includingthe speed. governor 148 for axially shifting the cam. 146 of Figures 3and 2 may also be employed to shift axially the cam 135 of Figure 1. Itis clear from the foregoing that the manual control 78, the speedcontrol 148, and the temperature and/or pressure controls 130 or 141 maybe inoperative under par ticular operating conditions; but the altitudecontrol including the bellows 82 actuated in response to variations in,compressor pressure. is effective at all times to actuate the fuelcontrol valve 72 in predetermined coordination with r the other controldevices.

It will be appreciated from the foregoing that the fuel and a,combustion chamber, a source of fuel under presmetering or controlsystem above described actuates the fuel valve, 72 to vary the rate offuel fiow as the product of two independent factors, or as a function oftwo-in: dependent variables, represented by the pull on'the rod 93 andby the effective ratio of the lever 74.- The SYS- te t nincludesfourmain control components: an altitude control 80. asindicated in Figure l; a manual control 78; a temperature (or pressure)control or 141; and a speed control 148. Moreover, in the preferredembodiment disclosed herein the altitude control is constantlyoperatingrupon the. rod 93, hence it determines at all times one of thefactors offuel flow, while the other factor (theratio of lever 74) isdetermined either by the manualf control, or by the temperature (orpressure) control, or the speed control. And a lost-motion connection'is. provided whereby the manual control may be over-riddenbythetemperature control and by the speed control, when predetermined valuesof temperature and speedconditions are reached. It will be further notedthat the variable-ratio lever mechanism comprising the levers 74 and 92and the movable pivots connected therewithoperate as a multiplyingdevice to which various signals, are fed or transmitted in response tocertain parameters of engine operation such as pressure, temperature,engine speed and the setting of the control lever 78' forthe purpose ofpositioning the fuel controlvalve 72. V

Theforegoing embodiments of the invention have been described forpurpose of. illustration and not as a limitation of, the, scope of theinvention. It is to be expressly understood that the invention may bepracticed in connection with various types of combustion engines orthermal, powerplant having different characteristics and distinctoperational requirements and limitations, and

that various modifications may be made to suit saiddiff erentrequirements, as will be obvious to those skilled in the art Withoutdeparting from the limits or scope of the invention as, defined in thefollowing claims.

Wherethe. claims are directed to less than, all of the ,eleme nts ofthecomplete system disclosed, they are into said combustion chamber, afirst means movable in' ,response to compressor pressure, a second meansmovable In response to a manually operable control member,

means operatively connected to said control valve and said firstandsecond means for multiplying the movements of said first and secondmeans and actuating said control valve, and means responsive to speedand another parameter of. engine operation and operatively connected tosaidvalve. for limiting the range of operation thereof.

2-. In a fuel control for an engine having a compressor sure, means forinjecting fuel into said combustion chamber including conduit meansconnecting said source and said combustion chamber, a control valve insaid conduit means movable tovary the rate of fuel flow to saidcombustion chamber, a'first means movable in response to compressorpressure, a second movable means subject to manual supervision, meansoperatively connected to said controlvalve for multiplying the movementsof said first and second means and varying the adjustment of saidcontrol valve in proportion to the product of said movements, and meansincluding servo devices responsive to compressor temperature and anotherparameter of engine operation, in mixed relation and operativelyconnected to said multiplying means for limiting the range of op- 7eration of said control valve in proportion to compressor pressure.

3. In a fuel control for an engine having a compressor and a combustionchamber, a source of fuel under pressure, means for injecting fuel intosaid combustion chamber including conduit means connecting said sourceand said combustion chamber, a metering orifice in said conduit means, acontrol valve movable to vary the effective flow area of said orificeand change the rate of fuel flow to the combustion chamber, a firstmeans movable in response to compressor pressure, a second movable meanssubject to manual supervision, means operatively connected to saidcontrol valve for multiplying the movements of said first and secondmeans and actuating said valve to vary the rate of fuel flow inproportion to the product of said movements, and additional meansincluding a three dimensional cam movable in one direction in responseto engine speed and in another direction in response to compressortemperature and operatively connected to said multiplying means toprovide a controlling signal for limiting the operating range of saidcontrol valve.

4. In a fuel control for an engine having a compressor and a combustionchamber, a source of fuel under pressure, means for injecting fuel intosaid combustion chamber including conduit means connected with saidsource and said combustion chamber, a valve in said conduit meansmovable to vary the rate of fuel flow to the combustion chamber, amultiplying device operatively connected to said valve for adjusting thesame to control the rate of fuel flow, means movable in response tocompressor pressure operatively connected to said multiplying device forfeeding thereto a signal to be multiplied, means subject to manualsupervision for modifying the output of said multiplying device, andmeans responsive to at least two parameters of engine operation andoperatively connected to said valve for limiting the range of operationthereof.

5. In a fuel control for an engine having a compressor and a combustionchamber, a source of fuel under pressure, means for delivering fuel fromsaid source to said combustion chamber including a fuel valve, amultiplying device operatively connected to said valve for positioningthe same and metering the fuel flow, means responsive to compressorpressure for transmitting a first signal to be multiplied to saidmultiplying device including operative connections thereto, meansresponsive to a manually adjustable control member and the temperatureat a predetermined point in the engine for transmitting additionalsignals to be multiplied to said multiplying device including operativeconnections thereto, and means responsive to a function of speed andtemperature at a predetermined point in the engine for maintaining thefuel-air mixture ratio within preselected limits.

6. In a fuel control for an engine having a compressor and a combustionchamber, a source of fuel under pressure, means for delivering fuel fromsaid source to said combustion chamber including a fuel valve, amultiplying device operatively connected to said valve for positioningthe same and metering in fuel flow, means responsive to compressorpressure for transmitting a first signal to be multiplied to saidmultiplying device including operative connections thereto, meansresponsive to a manually adjustable control member and means responsiveto the temperature at a predetermined point in the engine fortransmitting additional signals to be multiplied to said multiplyingdevice including operative connections thereto, and means responsive toa function of speed and temperature at a predetermined point in theengine operatively connected to said multiplying device for transmittingstill further signals thereto and including mechanism for disabling thesaid means responsive to the manually adjustable control member.

7. In a fuel control for an engine having a compressor anda combustionchamber, a source of fuel under pressure, means for delivering fuel fromsaid source to said combustion chamber including a fuel valve, amultiplying device operatively connected to said valve for positioningthe valve and metering the fuel flow, means responsive to compressorpressure for transmitting a first signal to be multiplied to saidmultiplying device including operative connections thereto, meansresponsive to manual supervision for transmitting a second signal to bemultiplied to said multiplying device including operative connectionsthereto, and means for limiting the range of variation of the fuel-airmixture ratio comprising means for modifying said second signal, saidlast mentioned means including mechanism responsive to a function ofspeed of the engine and temperature at a selected point in the engine.

8. In a fuel control for an engine having a compressor and a combustionchamber, a source of fuel under pressure, means for delivering fuel fromsaid source to said combustion chamber including a fuel valve, amultiplying device operatively connected to said valve for positioningthe valve and metering the fuel flow, means responsive to compressorpressure, a servomotor operatively connected to said device for feedingthereto a signal to be multiplied, said servomotor including a pilotvalve controlled by movement of said compressor pressure responsivemeans, means subject to manual supervision operatively connected to saidmultiplying device for feeding thereto a signal to be multiplied, meansmovable in response to the speed of rotation of said engine, meansmovable in response to the temperature at a preselected point in saidengine, means for mixing the movements of said speed and temperatureresponsive means for producing a resultant signal, and an operativeconnection for receiving said resultant signal and limiting the effectof said manually supervised means upon the multiplying device.

9. In a fuel control for an engine comprising a compressor and acombustion chamber, a source of fuel under pressure, means for injectingfuel into said combustion chamber including conduit means between saidsource and said combustion chamber, a control valve associated with saidconduit means and movable to vary the flow of fuel supplied to saidcombustion chamber, a multiplying device operatively connected to saidcontrol valve for varying the opening thereof, first means movable inresponse to compressor pressure operatively connected to saidmultiplying device for feeding thereto a signal to be multiplied, secondmeans movable in response to a parameter of engine operation, aservomotor operatively connected to said device for feeding thereto asignal to be multiplied, said servomotor including a pilot valvecontrolled by movements of said second means, adjustable means forvarying the effect of said second means and modifying the output of saidmultiplying device, a came movable in linear directions and transverselyof said linear directions, a means movable in response to the speed ofrotation of said engine including a servo system for moving said cam inone of said directions, means responsive to the temperature at apreselected point in said engine including a servo system for movingsaid cam in another of said directions, the motions of said camproducing a resultant signal, and a cam follower mechanism receivingsaid resultant signal and operatively connected to said multiplyingdevice for limiting the effect of said adjustable means on said controlvalve.

10. In a fuel control for an engine comprising a compressor and acombustion chamber, a source of fuel under pressure, means for injectingfuel into said combustion chamber including a control valve movable tovary the rate of fuel flow to said combustion chamber, a multiplyingdevice operatively connected to said control valve for varying theopening thereof, first means movable in response to compressor pressureoperatively connected to said multiplying device for feeding thereto asignal to be multiplied, second means subject to manual supervision formodifying the output of said multiplying device, a cam movable in lineardirections and transversely of said linear directions, a means movablein response to engine speed including a servo system for moving said camin one of said direction, means operatively connecting said cam to saidspeed responsive means for varying the response thereof uponrepositioning of said cam in its motion in said one direction, meansresponsive to another parameter of engine operation for moving said camin another of said directions, the motions of said cam producing aresultant signal, and a cam follower mechanism receiving said resultantsignal and operatively connected to said second means for overriding thesame and limiting the operating range of said control valve.

11. In a fuel control for an engine comprising a compressor and acombustion chamber, a source of fuel under pressure, means for injectingfuel into said combustion chamber including a control valve movable toregulate the rate of fuel flow to said combustion chamber, a multiplyingdevice operatively connected to said control valve for varying theopening thereof, first means movable in response to compressor pressureoperatively connected to said multiplying device for feeding thereto asignal to be multiplied, said pressure responsive means including amovable member and a servo mechanism for moving said member in onedirection as a linear function of compressor pressure, second controlmeans connected to said device for feeding thereto a signal to bemultiplied, a cam movable in linear directions and transversely of saidlinear directions, engine speed responsive means including a servosystem for moving said cam in one of said directions, means responsiveto the temperature at a preselected point in the engine for moving saidcam in another of said directions, the motions of said cam producing aresultant signal, and a cam follower mechanism operatively connected tosaid multiplying device for receiving said resultant signal and limitingthe signal fed to said device by said second control means.

12. In a fuel control for an engine having a compressor and a combustionchamber, a source of fuel under pressure, means for injecting fuel intosaid combustion chamber including a control valve movable to regulatethe rate of fuel fiow to said combustion chamber, a first means movablein response to compressor pressure, a second means movable in responseto a parameter of engine operation and a third means subject to manualsupervision for producing a plurality of control signals, meansoperatively connected to said control valve for multiplying said signalsand varying the adjustment of said control valve in proportion to theproduct of said signals, and means including servo devices responsive tocompressor temperature and another parameter of engine operation inmixed relation and operatively connected to said multiplying means foraltering one at least of said signals and limiting the range ofoperation of said control valve in proportion to compressor pressure.

13. In a fuel control for an engine having a compressor and a combustionchamber, a source of fuel under pressure, means for injecting fuel intosaid combustion chamber including a control valve adjustable to vary theflow of fuel to said combustion chamber, a first means movable inresponse to compressor pressure, a second means movable in response to aparameter of engine operation and a third movable means subject tomanual supervision for producing a plurality of control signals, meansoperatively connected to said control valve for multiplying said signalsand actuating said valve to vary the rate of fuel flow in proportion tothe product of said signals, and additional means including a threedimensional cam movable in one direction in response to engine speed andin another direction in response to compressor temperature andoperatively connected to said multiplying means to provide a controllingsignal for overriding one at least of said signals and limiting therange of said control valve.

14. In a fuel control for an engine having a compressor and a combustionchamber, a source of fuel under pressure, means for delivering fuel fromsaid source to said combustion chamber including a fuel control valve, amultiplying device operatively connected to said control valve forpositioning the valve and metering the fuel flow; means responsive tocompressor pressure, means responsive to a parameter of engine operationand manually operable control means including operative connections tosaid multiplying device for transmitting a plurality of signals to bemultiplied to said multiplying device, and means responsive to afunction of speed and temperature at a predetermined point in the enginefor altering at least one of said signals.

15. In a fuel control for an engine having an air intake system with acompressor therein and a combustion chamber, a source of fuel underpressure, a valve for controlling the flow of fuel from said source tosaid combustion chamber, means providing a signal responsive to thedischarge pressure of said compressor, means providing a signalresponsive to the speed of the engine, means providing a signalresponsive to temperature in said air intake system, and means fortransmitting said signals to said fuel control valve whereby the fuelflow is regulated as a function of the product of the compressorpressure signal and another of said signals during normal operation, andas a function of the pressure signal multiplied by the combined speedand temperature signals when the fuel-air mixture ratio tends to exceedpredetermined limits.

16. In a fuel control for a combustion engine having a compressor, asource of fuel under pressure, orifice means downstream of said source,a fuel valve for controlling said orifice means to regulate the flow offuel from said source to said engine, a valve-actuating mechanismincluding first means movable in response to com pressor pressureoperatively connected to adjust said valve and second movable meansoperatively connected to adjust said valve for varying the fuel fiowsubstantially in proportion to the product of said compressor pressureand the movement of said second means, a control mechanism subject tomanual supervision and 0peratively connected to said second means foractuating the same, a cam movable in linear directions and transverselyof said linear directions, means responsive to the speed of the enginefor moving said cam in one of said directions, means responsive to thetemperature at a preselected point in said engine for moving said cam inanother of said directions, the motions of said cam producing aresultant signal, and means receiving said resultant signal foroverriding said manually supervised control mechanism and actuating saidsecond means.

17. In a fuel control for a combustion engine having a compressor, asource of fuel under pressure, an orifice downstream of said source, afuel valve for controlling said orifice to regulate the flow of fuel tosaid engine, first means movable in response to compressor pressureoperatively connected to said valve to transmit thereto a first controlsignal and second movable means operatively connected to said valve totransmit thereto a second control signal for metering the flow of fuelto the engine as the product of both of said signals, a controlmechanism responsive to a parameter of engine operation for actuatingsaid second means, and means responsive to a function of a plurality ofparameters of engine operation for overriding said control mechanism andtaking over operation of said second means.

References Cited in the file of this patent UNITED STATES PATENTS2,822,666 Best Feb. 11, 1958

